Tank valve



FIG. 1 is a side elevational view of a tank valve showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is an elevational view taken from the side opposite that shown in FIG. 1;

FIG. 5 is a bottom view thereof; and

FIG. 6 is a top view thereof. 

The ornamental design for a tank valve, as shown. 